Influence of dissolved oxygen on accumulation of lipid and secretion of citric acid by Yarrowia lipolytica fermentation

Among oleaginous microorganisms,Yarrowia lipolytica can convert excess carbon source from the medium into lipids stored in the cells and secrete large amounts of citric acid.Dissolved oxygen(DO)concentration in the culture medium during fermentation process was controlled by stirring speed and ventilation which was selected for five levels i.e.:5%,10%,20%,30% and uncontrol.The results indicated that the increase of dissolved oxygen resulted in an increased production of lipid and citric acid of Yarrowia lipolytica.However,the maximum yield of lipid and citric acid was achieved by normal fermentation without controlling of dissolved oxygen concentration. The obtained lipid content and citric acid concentration were 11.62%(w/w)and 21.0 g/L respectively.Furthermore,dissolved oxygen concentration can also affect the lipid fatty acid composition.High dissolved oxygen could promote the increase of oleic acid content,and the highest content of oleic acid was 48.62% which was obtained in the uncontrol level. This study would provide an important basis for the control of dissolved oxygen concentration in lipid accumulation by Yarrowia lipolytica.